Harvesting the fruits of all that labor and preparing for winter keep the September gardener busy. Deadheading, clearing away debris, and composting spent annuals all help to prevent future problems with pests and diseases.
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Apples
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Many apple varieties are ready for harvest (assuming the birds have left any uneaten). Other apple varieties will need some colder weather to sweeten. If you notice small brown, corky areas under the skin, it is called bitter pit. Bitter pit, like blossom end rot in tomatoes, is caused by a calcium deficiency early in the spring. In this case, however, the condition can be treated on future crops by spraying the leaves with calcium nitrate just after bloom and again one or two months later. Use one tablespoon per gallon of water.


Carrots

Carrots prefer loose soil, but shorter varieties perform well enough in our heavy clay. The addition of compost can help aerate the soil and provide valuable nutrients. Carrots should be planted no more than 1/2” deep and plants should be thinned to 3” apart, to avoid forking and twisting. Water regularly but allow some drying to prevent cracking. Successive plantings provides an ongoing harvest. Carrots can be planted between landscape perennials for productive use of space.


Cover crops

Areas of the garden that will be left bare over the winter are better planted with cover crops. Cover crops help maintain important soil microorganisms that will, in turn, support your spring and summer crops next year. Fava beans are an excellent choice in the Bay Area.


Leafcutter bees

If rose leaves are exhibiting neat round or oval holes in them, it is probably the beneficial leaf cutter bee and should be ignored. The sections of leaf are used to line brood cells, which are also filled with nectar and pollen.
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Mosaic virus

Squash and cucumber plants are susceptible to a disease carried by aphids and cucumber beetles. Mosaic virus causes leaves to become mottled and stunts plant growth. Fruit may become white. Diseased plants should be removed and put in the trash. Do not add to the compost pile.


Powdery mildew

As nights become cooler, it is common for powdery mildew to strike. Affected leaves should be removed and thrown in the trash, and overhead watering should be avoided.


Rats

Gnawed fruit, empty snail shells, and tiny black pellets are all signs of roof rats. These pests can infiltrate your attic, crawl space, garage, storage shed, and trees. Rat traps are an excellent way to remove resident rats. Keeping pet and livestock food sealed up and harvesting crops as soon as possible will help make your yard less desirable to the local rat population. Since rats can carry serious diseases and damage electrical wiring, it is worth the effort to get rid of rats.


Spider mites

If leaf stippling and tiny webs are seen, spider mites are probably the reason. Spider mites prefer dusty conditions, so spraying infested plants with the hose can help. Using broad spectrum pesticides is not recommended because they will kill the spider mites’ natural predators. Heavy spider mite infestations can be treated with insecticidal soap or horticultural oil.


Tomatoes

Any yellow flowers produced by your tomatoes now will not have time to mature before temperatures cause fruit to turn mealy before maturing. Instead, remove those flowers to encourage plants to put all their energy into any fruit that is already on the vine.


Vegetables

September is the time to plant many winter crops, including artichoke, arugula, beets, bok choy, cabbage, carrots, cauliflower, chard, cilantro, collards, dill, fennel, kale, leeks, parsnips, peas, radishes, rutabagas, spinach, and turnips.


Enjoy the fruits of your labor!

Be sure to put on your sunscreen, wear a hat, and keep those tools clean and sharp as you enjoy the garden in June!

May is one of the busiest months in the garden. Temperatures have warmed enough for us to begin planting in earnest. Weeds, pests, and beneficial insects are out in force. And it's gorgeous outside!                                                                                                           


Aerate the soil                                                                                                          

Our San Francisco Bay Area soil is heavy clay. This means it can hold on to lots of water and nutrients, but it can be difficult for roots, earthworms, and soil microorganisms. You can hire a professional aerator to come in with their heavy equipment to punch plugs out of your soil. While the machine creates its own soil compaction, the plugs really do make a big difference in soil health. Or, you can do what I do, which is to contact your local tree trimmer and ask for a load of tree trimmings. It won’t be the pretty bagged variety, but it will contain chipped twigs, leaves, stems and branches that can be spread on top of the soil as a mulch that will profoundly improve your soil structure. In 2012, when we bought our home, the soil was more like concrete. Now, thanks to mulches of tree trimmings, my soil is rich and black, loose, and filled with earthworms and beneficial microorganisms. For free.


Bees

Bees are very active in May. There is simply so much pollen and nectar to collect! Sometimes, a honey bee colony may swarm. If you see a swarm, don’t panic. As in any other time when working around bees, remain calm, move gently, and give them their space. Contact your local Bee Guild or  Master Gardeners to have swarms removed.


Bulbs and other flowers

If flowering bulbs were looking crowded during the recent bloom time, delay digging them up to separate until after all the foliage is completely dry. Bulbs pull important nutrients from these leaves to help start up again next spring. Bulbs that are dug up and separated can be replanted in a new location, gifted to friends, or stored in a cool, dry, dark location until fall. If you want fall blooms, plant now.


Container plants

They are countless varieties of plants that perform well in containers. Do them all a favor in May and get them off that soon-to-be hot concrete patio. Creating even the smallest space under container plants can reduce the roasting effect, which means they will need less water. Speaking of water, warmer temperatures mean container plants will start drying out more quickly. Water as needed.


Deadheading

Many flowers are in full bloom in May. To encourage plants to continue creating blooms, remove spent flowers as soon as they are seen. This also reduces habitat for many pests and diseases. Pinch back borage, petunias, and fuchsias to prevent plants from becoming top heavy.


Fireblight

May is the time fireblight shows itself in the Bay Area. Fireblight is a bacterial disease that makes plants look as though they had been damaged by fire. It attacks apples, pear and quince, most often, but can also infect ornamentals, such as toyon and pyracantha. Very often, the growing tip folds over into a shepherd’s crook shape. Fireblight can kill a mature tree, so complete removal of any diseased tissue is critical. Sanitize pruners with a household cleaner, such as Lysol, between each cut to prevent reinfection. The final cut should be 8-12 inches below the diseased area.


Fruit trees

May should be the time when fruit trees are covered with immature fruits. Thin those fruits now or regret it later. Too much fruit in one place means none of them taste as good as they might have. It also creates habitat for pests and disease. Apples should be thinned to no more than 3 fruits to a cluster, or one fruit for every 6 inches of branch. Apricots and other stone fruits need 4-6” between fruits for optimal growth, flavor, and sweetness. Also, be sure to check apples for codling moth damage.


Lawns

If you still have a lawn, be sure to water it as early in the morning as possible. That way, the water isn’t lost to evaporation and the grass has time to dry out during the day, reducing the chance of fungal diseases. For the most part, I use water from my washing machine to water my lawn and it has been working very well. Check the lawn for weeds such as spurge, burclover, and whatever happens to invade your neighborhood. When mowing, set the blade height as high as you are comfortable with in summer. Taller grass shades the soil. This reduces evaporation and it makes the soil more comfortable for valuable  earthworms and microbes.


Mulch and compost

Compost and mulch are two of the best things to add to any landscape. They add valuable nutrients to the soil, improve soil structure, and stabilize soil temperature. In our heavy clay soil, mulch prevents the baked concrete look we have come to expect in summer. [An important note about soil additives - while it may sound right to add sand to clay soil, to reduce compaction, it ends up creating concrete. Don’t do it!]


Slugs & snails

Slugs and snails can devastate young May seedlings. Applying non-toxic slug and snail bait lightly around new planting areas can save the crop. While there are more effective baits, those made with iron phosphate are not toxic to pets and wildlife and I have found they work well enough.


Soil test

Before you start applying fertilizers and fungicides, collect a soil sample and send it out to a lab. [I use the UMass lab, but there are many to choose from]. The information provided in soil test results is invaluable. More often than not, your soil does not need more of all the nutrients found in a bag of fertilizer. It may only need some, or, in my case, it only needed iron because it held an excess of everything else. Simply adding more fertilizer can create nutrient imbalances that make it difficult for plants to absorb what they need. Get a soil test. It’s worth it.


​Start planting!

This is the most welcome news of the season in the Bay Area. Nearly all summer growing plants (tomatoes, cucumbers, melons, squash, beans, corn, and peppers) can be put in the ground in May. If you are using transplants, be sure harden them off gradually or they may lose much of their vigor and productivity. Hardening-off simply means placing them outdoors in a protected location for a few hours. Slowly increase the time over a couple of weeks. Be sure to stake tomato plants now, while they are small. This can be done in tandem with quarantining new plants. And add straw under melon, squash, and strawberry plants to reduce fungal infection.


Verticillium wilt

If verticillium wilt occurred last year, it is important to plant members of the nightshade family (tomatoes, potatoes, peppers and eggplant) someplace else. Verticillium wilt is a fungal disease that shows as yellowing older leaves, at first. Then, as the disease spreads, wilting occurs. Young plants nearly always die. Since the fungal spores can remain in the soil for 10-15 years, crop rotation is the best prevention.


Water

California’s drought is continuing, despite the fair bit of rain we have received so far. The truth is,  the Golden State has always been drought-prone and we would be wise to learn to live accordingly. When water restrictions were first implemented, I vowed to take meaningful steps to reduce our water consumption. As a result, we now use only 25% of the water we used to use! Surprisingly, my garden has not suffered and neither have we. These steps can help you conserve water while still caring for the garden:

• Collect water from the bath or shower as it warms and use it to water plants.
• Collect water from boiling pasta and vegetables and use it to water plants.
• Inspect spigots, hoses, sprinkler and drip irrigation systems for leaks.
• Water early in the morning, and water deeply and less frequently.
• When adding new plants, pick varieties that are suited to the local microclimate.
• Avoid urban drool by setting sprinklers to go through a series of pulses. Start with just a few minutes to allow hydrophobic soil to absorb the water, rather than run off.
• Apply organic mulch or wood chips everywhere.
• Turn off faucets while washing hands, brushing teeth, or shaving.
• Use only the minimal amount of fertilizer. Excess fertilizer forces plants to grow faster than they can maintain without a significant increase in water use. Without a soil test from a reputable lab, you don't know if fertilizers are needed.
• Be aware that the drought brings more wildlife into yards as they search for food and water. You may want to provide a water source, such as a birdbath, but be sure to not create a mosquito breeding ground.

Weeds

Just as young garden plants are really kicking it into high gear in May, so are the weeds. Take my word for it, pulling them while they are small, and before the soil is baked, is much easier than later. Weeds take precious water and nutrients from garden plants. In most cases, the sooner they are gone, the better.


So, put on the hat and sunscreen and get out there in that May garden!